runtime/bin/vmservice/client/lib/src/elements/curly_block.html

<polymer-element name="curly-block">
  <template>
    <style>
      .idle {
        display: inline-block;
        color: #0489c3;
        cursor: pointer;
      }
      .busy {
        display: inline-block;
        color: white;
        cursor: wait;
      }
    </style>
    <template if="{{ expanded }}">
      <template if="{{ busy }}">
        {<div class="busy">&nbsp;&nbsp;&#8863;&nbsp;&nbsp;</div>
        <br>
        <content></content>
        }
      </template>
      <template if="{{ !busy }}">
        {<a on-click="{{ toggleExpand }}"><div class="idle">&nbsp;&nbsp;&#8863;&nbsp;&nbsp;</div></a>
        <br>
        <content></content>
        }
      </template>
    </template>

    <template if="{{ !expanded }}">
      <template if="{{ busy }}">
        {<div class="busy">&nbsp;&nbsp;&#8862;&nbsp;&nbsp;</div>}
      </template>
      <template if="{{ !busy }}">
        {<a on-click="{{ toggleExpand }}"><div class="idle">&nbsp;&nbsp;&#8862;&nbsp;&nbsp;</div></a>}
      </template>
    </template>
  </template>
  <script type="application/dart;component=1" src="curly_block.dart"></script>
</polymer-element>